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March

Winter Storm Threat: March 13-14 (Final Call)

The wintry mix of snow, sleet, and rain appears to be creeping closer to I-95 on the models, so I tightened up the gradient a bit to reflect lower totals from D.C. to Baltimore. The same is true for Long Island, and could be true for eastern New Jersey and New York City as well.

On the flip side, higher QPF across most of Pennsylvania into northern New Jersey and eastern Upstate New York increased the snow total forecast for these areas. Some small increases also occurred along the Appalachians.

Highest risk is still how far north and west the sleet/rain mixing line gets tonight, which could cut deeply into totals along I-95. Once you get far enough north and west and enter the “safe zone” where no mixing is expected, locally higher snow totals are possible.

Oh yeah, and don’t forget about those winds, especially along the coast. Gonna be fun.

Winter Storm Threat: March 13-14 (Initial Call)

As has been the pattern of recent Marches, we in the Mid-Atlantic find ourselves with a late-season snow storm that contains significant snowfall. While the storm evolution may not be classic, it seems that we will see a fairly common snowfall distribution, with the highest snow totals hitting mostly north and west of I-95 while areas south and east see more of a rain and a wintry mix.

The two main questions are where the rain/snow line ends up, and how warm will the surface temperatures be when the snow is falling. For the D.C. to Philadelphia corridor, this will mean a lot. The models differ on just how cold it is along the I-95 corridor as the precipitation is falling, which is where most of the uncertainty with this forecast lies.

The QPF is also a bit of an issue, but taking a model blend seems to be the best way to go at this point. I wouldn’t count hugely on anomalous pockets of minimal QPF, and I’m sure there will be some area that gets sweet deformation banding and ends up with more snow than expected.

Winter Storm Threat: March 4-5 (Only/Final Call)

Can this be the last one, please? Near normal highs are going to feel like heat waves this month.

20150304-05_MAsnow_final

Most uncertainty is going to come from the changeover from rain to sleet to snow. A slower cold push and/or prolonged sleet could cut down on totals. Regardless of the fact that there’s more downside than upside, it should be a fun storm. Once the changeover to snow does occur, the snow rates should be pretty good, so I’m not too worried about getting accumulations started in the more southern areas when the changeover isn’t until after sunrise. A layer of sleet to start should help the initial snow accumulations as well.

Winter Storm Threat: Mar 16-17 (Final Call)

Not much change from the last map… mostly some expansion of the 4-8″ contour over the mountains and cutting back totals a little bit on the parts of the fringes. I don’t trust how bullish the models are on the snow maps because it looks like temperatures may end up a bit warmer than the raw 2mt in the evening, taking the snow longer to start accumulating. Maybe the front-end stuff will be heavy enough to stick earlier, but I have my doubts.

20140316-17_MAsnowFinal

Still some wiggle room with this, but models are coming to a nice consensus regarding the track, which is pretty much where my snow map is now and was yesterday. There appears to be more upside potential than downside with this event in the 1-4″ areas and up in the mountains, especially if you trust the higher QPF model solutions.

Winter Storm Threat: Mar 16-17 (Initial Call)

With what is hopefully our last snow threat for the season in the greater D.C. area, there is still a fair amount of uncertainty with the ultimate track of the system in addition to how wet it is. Lower than normal confidence with this forecast, which favors the Euro more than the GFS.

20140316-17_MAsnowInitial

My forecast seems somewhat conservative compared to what some of the models are showing, so I imagine there is probably more upside potential than downside with this disturbance. This thing could still shift some 30-50 miles north or south, so don’t get too hung up with exactly where all the contour edges are at this point.

Winter Storm Threat: Mar 2-3 (Final Call)

UPDATE March 2nd, 2pm EST: After seeing the latest model forecasts and trends, I would probably shift the 4-8″ and 8-12″+ contours south by about 15-20 miles.

Shifting everything a bit south from the initial forecast and added locally 12″+ wording for the mountains. Accumulations are for snow and sleet, though it will be a mostly snow event in the higher total areas.

20140302-03_MAsnowFinal

If the sleet holds out for longer in the morning then totals may be cut down, but on the flip side once the cold air does arrive, we could start to see some higher ratio snowfall.

Models may continue to drift south, but I don’t think it will go much further south if they do. For the DC area, expect some rain to start tomorrow afternoon, which may briefly change over to freezing rain before the sleet moves in. After some sleet, over to all snow probably a little before morning rush hour… then snow through the afternoon hours.

And then we get hit by frigid air. Joy.

Winter Storm Threat: Mar 2-3 (Initial Call)

Meteorological spring is here, but winter isn’t done with us yet. Most of the region will actually start off as rain, but a very strong cold air mass will push southward, bringing the low-level air below freezing and changing areas over to freezing rain and sleet before finally transitioning to snow. The models are handling the speed of this cold air push differently, so there is still a fair amount of wiggle room with the snow totals.

20140302-03_MAsnowInitial

There is still room for this to move north or south by a decent margin. I’ll have a final update after the 18z models come in.